In-Law Preferences for Similarity: Comparing Parent and Child Preferences for In-Law/Intimate Partner Similarity

Abstract

Parents want daughters- and sons-in-law who are similar to their children, and children want spouses who are similar to themselves. In turn, the question arises: Do parents agree among themselves on how much similarity they desire in their prospective in-laws concerning their children? Moreover, do parents and children agree on the level of similarity they desire in an in-law and a spouse, respectively? Furthermore, to exercise an in-law preference for similarity, parents need to assess how their children score in traits deemed desirable in a spouse. This raises the question of whether mothers and fathers perceive their children similarly, and whether they perceive their children in the same way their children perceive themselves in these traits. The current study aimed to address these questions using a sample of 356 families from China, focusing on four desirable traits: good looks, good providers, good economic prospects, and good family background. Our results indicated that parents preferred sons- and daughters-in-law who were similar to their children, and mothers and fathers concurred on the level of similarity they desired between their children and their in-laws. Additionally, parents desired as much similarity between their children and their in-laws as their children desired between themselves and their spouses. Furthermore, we found that mothers and fathers concurred on how they perceive their children across the four desirable traits. Finally, both parents scored their children higher in these traits than their children scored themselves.

Introduction

Parents play an important role in their children's mate choices, with parents preferring their prospective in-laws to have specific qualities (Apostolou, 2010; Wang & Apostolou, 2017a). What parents prefer their in-laws to have is not always the same as what their children prefer their spouses to have, leading to disagreement between the two parties (Trivers, 1974). One trait that is preferred by both parents and children in a prospective in-law or spouse, respectively, is similarity (Luo, 2017; Wang & Apostolou, 2017a). Accordingly, the first objective of this study is to address the question of whether parents and children disagree over this dimension; that is, whether children want their prospective spouses to be more similar to them than their parents want their children to be with their prospective in-laws. It also aims to examine whether mothers and fathers agree on how much similarity they want their in-laws to have with their children. Additionally, in-law preferences for similarity involve assessing children's qualities, raising several questions, including whether parents agree with each other on how they perceive the qualities of their children and whether parents assess these qualities in their children the same way as their children assess themselves in these qualities. The second objective of the current study is to address these questions. Parental influence over mating and in-law preference for similarity could be understood within an evolutionary theoretical framework that we will discuss next.

Parental Influence Over Mate Choice

Parents and children are genetically related, sharing overlapping genetic interests (Trivers, 1974). This implies that what benefits one party is also beneficial for the other. For example, in terms of mate choice, individuals prefer partners who are kind and understanding, anticipating that such partners would treat them well and offer support during challenging times (Buss & Schmitt, 2019). Consequently, individuals with spouses possessing these qualities are more likely to be treated well and receive support from their partners and thus more likely to pass on their genetic material to future generations, known as fitness, compared to those with partners lacking these qualities. Yet, individuals’ genes are also shared with their parents, prompting them to prefer daughters- and sons-in-law who do well in these dimensions. Still, as the mating market is marked by deception (Haselton et al., 2005), children may make mate choices that could compromise their fitness and, consequently, their parents’ fitness. On the other hand, parents, possessing more life and relationship experience, may intervene in their children's mating decisions to help them make more informed choices, benefiting both parties (Apostolou, 2017a).

Nevertheless, parents and children are not genetically identical, leading to situations where their genetic interests do not completely align (Trivers, 1974). This implies that there are cases where what benefits one party may not be as beneficial for the other, resulting in disagreement between them. Such disagreement is evident in mate choice, where the ideal spouse for children may not align with the ideal in-law for parents (Apostolou & Wang, 2018; Bovet et al., 2018; Lefevre & Saxton, 2017). For instance, individuals share 50% of their genes with their daughters and sons, but only 25% with their granddaughters and grandsons. Consequently, genetic quality holds greater importance in a prospective spouse than in a prospective in-law (Apostolou, 2008). If prospective spouses exhibit poor genetic quality, individuals risk reducing the chance that 50% of their genes are represented in future generations, as opposed to 25% if their prospective in-laws have poor genetic quality. This discrepancy leads to parents and children placing different values on good genetic quality in a prospective spouse, influencing distinct compromises to achieve desirable outcomes (Apostolou, 2017b). Consequently, children, if left to make choices independently, may select spouses not necessarily ideal for their parents, who, in turn, have an incentive to influence their children's mating decisions to ensure choices that align with parental preferences (Apostolou, 2017a). Overall, converging and diverging genetic interests make it beneficial for parents to exert influence over their children's mating decisions.

The Importance of Similarity

Marriage constitutes a long-term partnership between two individuals working toward a common goal, typically involving having and raising children (Coontz, 2006). For this goal to be achieved, good cooperation is needed between the parties involved, with one key predictor of such cooperation being similarity (Luo, 2017). In particular, dissimilarity between partners may cause friction that harms cooperation. For instance, if one partner scores very high and the other very low in extroversion, frequent disagreements may arise on how to spend leisure time. Thus, the dissimilarity between intimate partners is likely to compromise the chances that an intimate relationship leads to family formation, resulting in strong selection pressures shaping mate preferences to favor individuals seeking mates similar to themselves across different dimensions (Buss & Schmitt, 2019; Luo, 2017).

In influencing mate choice, parents are interested in establishing long-term intimate relationships with spouses of their choosing, envisioning the development of grandchildren and fostering cooperation between two previously unrelated families (Apostolou, 2010). Consequently, it would be beneficial for parents to select spouses for their children who are similar to them across various dimensions, as such similarity is expected to lead to more stable relationships. In turn, selection forces have shaped in-law preferences, leading parents to prefer daughter- and son-in-law individuals who resemble their children (Wang & Apostolou, 2017b).

Given that individuals interact more frequently with their spouses than with their in-laws, similarity is deemed more beneficial in a prospective spouse than in a prospective in-law. Consequently, we predict that children would prefer their prospective spouses to be more similar to them than their parents would prefer their prospective in-laws to be similar to their children. Moreover, there is no theoretical reason to believe that similarity between children and in-laws would be more or less beneficial for mothers or for fathers. Accordingly, we further predict that parents would agree among themselves on the level of similarity they would prefer their children to have with their in-laws. To the best of our knowledge, there has not been any study that has attempted to test these predictions.

How Parents Evaluate Their Children Versus How Children Evaluate Themselves

One related question that we aim to answer in the current research is whether parents agree among themselves on how they evaluate their children and whether parents evaluate their children in the same way as their children evaluate themselves. Starting with the former question, there are no reasons to believe that mothers would accrue more or fewer fitness benefits by evaluating their children differently than fathers. Accordingly, we predict that fathers and mothers would perceive their children similarly.

Regarding the question of whether parents evaluate their children as their children evaluate themselves, there are at least three different possibilities. (a) To begin with, it would be advantageous for people to accurately evaluate both themselves and their children over desirable traits, so children and parents would not differ in their evaluations. (b) Moreover, parents prioritize certain traits, such as good family background, more and others, such as good looks, less in a prospective in-law than their children do in a spouse. One possible way to influence children's mate choices to align with parental preferences is to evaluate their children as less good-looking and of a better family background than their children would evaluate themselves in these dimensions. In this way, parents would seek in-laws who score lower in good looks and higher in good family background than their children would when searching for mates. This argument predicts that evaluations of desirable traits would differ between parents and children only for conflicting traits.

(c) Additionally, in order to survive and reach sexual maturity, children require considerable, reliable, and prolonged parental investment (Lancaster & Lancaster, 1987). That is, parents need to continue diverting considerable resources to their children to ensure their survival and reproduction. Thus, there should be mechanisms that motivate them to do so. One such possible mechanism is for parents to perceive their children as good investments so that they keep diverting resources to them. That is, parents would tend to see their children as having good qualities, making them more willing to invest in them. This bias would also manifest in assessing children across traits considered desirable in a mate, predicting that people will perceive their children as scoring higher in desirable qualities than their children see themselves.

The Current Study

The present study aimed to test the prediction that parents prefer their daughters- and sons-in-law to be similar to their sons and daughters. Moreover, it aimed to test the prediction that children would prefer their prospective spouses to be more similar to them than their parents would prefer their in-laws to be similar to their children. Furthermore, it aimed to test the prediction that mothers and fathers agree on how much similarity they want their in-laws to have with their children. Additionally, it aimed to test the prediction that mothers and fathers would evaluate their children similarly, as well as to examine whether parents evaluate their children the same way as their children evaluate themselves over desirable traits.

Method

Participants

The current study utilized a dataset, part of which was previously analyzed in a study by Wang and Apostolou (2017b). Specifically, students enrolled in psychology courses at three Chinese universities were recruited and contacted their parents to participate in a research study on mate and in-law choice. Parents who agreed to participate were provided with the study's link. To differentiate between couples, each family was assigned a unique number, and participants entered this number before responding to the survey. The sample consisted of 356 Chinese families, comprising 712 parents and 390 children (234 daughters and 156 sons). The mean age of mothers was 46.6 (SD = 4.0), and the mean age of fathers was 48.5 (SD = 4.2). All parents had only one child. The male children had a mean age of 21.8 (SD = 3.3), and the female children had a mean age of 20.1 (SD = 2.1).

Materials

The survey for parents consisted of three parts. In the first part, participants were asked to fill in their demographic information. In the next part, participants were asked to rate how desirable they considered a set of 88 traits identified by Wang and Apostolou (2017a) in the prospective spouse for their children including good looks, good provider, good economic prospects, and good family background, using a 4-point Likert scale (0—unimportant, 1—somehow important, 2—important, 3—indispensable). In the third part, parents were asked to rate their children in four dimensions, namely good looks, good provider, good economic prospects, and good family background on the following scale: 1—very low, 7—very high. The survey for children had also three parts: in the first part, children indicated their demographic information, in the second part, they rated the 88 traits in a prospective spouse, and in the third part, they rated themselves in the four dimensions of interest, using the same scales as in the case of parents.

Data Analysis

The analysis was performed using SPSS version 28. We employed Pearson's product–moment correlation to correlate the scores that mothers gave when assessing their children over desirable traits with the respective scores of fathers. This analysis allowed us to examine how similarly mothers and fathers perceived their children. Additionally, we compared the mean scores for each trait that mothers gave for their children with the mean scores fathers gave, using the paired-samples t-test. This analysis enabled us to determine whether mothers perceived their children as scoring significantly higher or lower in desirable traits than fathers. It is important to note that we employed the paired-samples t-test because mothers and fathers were part of the same family, and their answers were not independent.

Furthermore, we correlated the scores that parents gave for their children in the four desirable traits with the scores their children gave for themselves. This approach allowed us to examine if parents perceived their children in the same way as their children perceived themselves. Additionally, we compared the mean scores that parents gave for their children in the four traits with the mean scores their children gave for themselves, using the paired-samples t-test. This comparison allowed us to investigate whether parents perceived their children as scoring higher or lower in desirable traits than their children perceived themselves.

Moreover, we correlated the scores that parents gave for their children in desirable traits with the scores in desirable traits parents gave for prospective in-laws. This analysis aimed to determine whether parents wanted their prospective in-laws to possess similar qualities to their children. We also correlated the scores that children gave for themselves with the scores they gave for their prospective spouses. Additionally, we compared the correlation coefficients of mothers and in-laws with the correlation coefficients of fathers and in-laws using Fisher's z method. This comparison aimed to examine whether mothers and fathers agreed on how much similarity they desired between their children and in-laws. Furthermore, we employed Fisher's z method to compare the correlation coefficients of parents and in-laws with the correlation coefficient of children and prospective spouses. This analysis aimed to examine whether children desired their spouses to be as similar to them as their parents desired their in-laws to be with their children. All significant correlation differences were computed using a calculator that has been developed for this purpose (https://www.psychometrica.de/correlation.html).

Results

Do Mothers and Fathers Agree on How They See Their Children's Desirable Traits?

Based on the t-test results, it is evident that mothers generally did not tend to perceive their children as scoring significantly higher or lower in desirable traits compared to fathers (Table 1). There was one exception, however, where mothers tended to evaluate the looks of their sons higher than fathers did. Furthermore, all correlations between fathers and mothers regarding daughters were significant, with positive correlation coefficients, albeit relatively small in size. Concerning sons, the correlations were not significant for good looks and good providers, but they were significant and small for good economic prospects and good family background. These results could be interpreted to suggest some agreement between fathers and mothers in how they perceive their children across the four assessed traits. However, there was considerable disagreement, and this discrepancy was not consistent; in other words, mothers did not consistently perceive their children as scoring higher or lower than fathers.

Table 1.

Mean Scores of How Mothers and Fathers Perceive Their Children or the Children Themselves.

	Daughters	Mothers	Fathers					Sons	Mothers	Fathers
Desirable traits	M (SD)	M (SD)	M (SD)	p-value	d	r	p-value	M (SD)	M (SD)	M (SD)	p-value	d	r	p-value
Good looks	4.70 (0.89)	5.77 (0.94)	5.74 (0.93)	.674	0.03	.33	<.001	4.52 (1.07)	5.77 (0.89)	5.33 (1.02)	.001	0.33	.03	.752
Good provider	4.46 (1.03)	5.27 (1.09)	5.14 (1.06)	.107	0.11	.32	<.001	4.65 (1.14)	5.46 (0.93)	5.33 (1.02)	.331	0.10	.10	.324
Good economic prospects	5.06 (1.04)	5.97 (0.84)	5.95 (0.82)	.680	0.03	.35	<.001	5.24 (1.16)	6.12 (0.75)	6.05 (0.90)	.501	0.07	.24	.015
Good family background	4.49 (0.95)	5.03 (1.12)	4.95 (1.02)	.324	0.06	.39	<.001	4.48 (1.12)	5.03 (1.05)	4.88 (1.17)	.248	0.11	.35	<.001

Note. The (r) columns refer to correlations in scores between mothers and fathers for their daughters and their sons respectively.

The means refer to the scores participants gave to individual traits and could range from 1 to 7.

For each comparison, the first column of p-values refers to the t-test and the second to the correlation.

Do Parents and Children Assess the Latter's Qualities the Same?

From Table 1, it is evident that, for all traits, both mothers and fathers assigned higher scores to the four desirable traits than their children assigned to themselves. Table 2 further reveals that all differences were statistically significant. With the exception of the good provider trait for daughters and fathers, all the parent–daughter correlations were significant, with coefficients ranging from small to small to moderate in size. Regarding sons, the majority of correlations were not significant, and those that were significant were small in size. These findings indicate that parents tended to perceive their children as scoring higher in desirable traits than their children perceived themselves. Nonetheless, there was some agreement; for instance, if parents perceived their children as having a good family background, their children also perceived themselves as having a good family background.

Table 2.

Mean Comparisons and Correlations Between Parents and Children's Self-Rating Scores.

	Mothers/daughters				Mothers/sons				Fathers/daughters				Fathers/sons
Desirable traits	p-value	d	r	p-value	p-value	d	r	p-value	p-value	d	r	p-value	p-value	d	r	p-value
Good looks	<.001	.93	.20	.002	<.001	1.02	.24	.014	<.001	.96	.30	<.001	<.001	.91	.08	.398
Good provider	<.001	.60	.20	.003	<.001	0.57	.08	.434	<.001	.48	.07	.315	<.001	.43	-.07	.495
Good economic prospects	<.001	.77	.21	.001	<.001	0.67	.13	.205	<.001	.78	.27	<.001	<.001	.54	-.04	.691
Good family background	<.001	.47	.38	<.001	<.001	0.44	.32	<.001	<.001	.43	.39	<.001	.003	.28	.20	.042

Note. For each set of comparisons, the first p-value column refers to the paired-samples t-test and the second to the Pearson's correlation.

For each comparison, the first column of p-values refers to the t-test and the second to the correlation.

Do Parents Want Their In-Laws to Be Similar to Their Children?

From Table 3, it is evident that all the correlations between parents and their prospective sons-in-law were significant, with the coefficients being positive and small. Concerning mothers and prospective daughters-in-law, only the good family background exhibited significance, with a positive and moderate correlation coefficient. Regarding fathers and prospective daughters-in-law, good providers and good family background showed significance, with positive and small coefficients. The good family background was significant in all comparisons and, with the exception of the father–daughter-in-law comparison (where it was the second-highest), had the highest correlation coefficient. These findings indicate that parents desire their children to be to some degree similar to their prospective spouses, especially concerning good family backgrounds.

Table 3.

Correlations Between Scores of Children and Scores of Prospective Spouses and In-Laws.

	Daughters/husbands		Mothers/sons-in-law		Fathers/sons-in-law		Sons/wives		Mothers /daughters-in-law		Fathers/ daughters-in-law
Desirable traits	r	p-value	r	p-value	r	p-value	r	p-value	r	p-value	r	p-value
Good looks	.15	.024	.21	.001	.15	.022	.23	.022	.14	.148	.09	.395
Good provider	.21	.001	.23	<.001	.19	.003	.00	.995	.14	.168	.31	.001
Good economic prospects	.25	<.001	.25	<.001	.22	<.001	.09	.352	.05	.606	.10	.326
Good family background	.38	<.001	.28	<.00	.29	<.001	.30	.002	.41	<.001	.28	.004

Do Mothers and Fathers Agree on How Similar They Want Their In-Laws to Be With Their Children?

Comparisons between correlation coefficients for mothers and in-laws and fathers and in-laws were not significant (Table 4). These results indicate that mothers and fathers did not disagree among themselves regarding how much similarity they desired between their prospective daughters- and sons-in-law and their children.

Table 4.

Comparisons of the Correlation Coefficients of Mothers and Fathers.

	Mothers vs fathers (daughters)	Mothers vs fathers (sons)
Desirable traits	p-value	p-value
Good looks	.505	.720
Good provider	.652	.204
Good economic prospects	.732	.355
Good family background	.907	.295

Do Children Want Their Spouses to Be More Similar to Them Than Their Parents Want Their In-Laws to Be With Their Children?

In Table 3, we presented the correlation coefficients of children and their spouses, as well as the correlations of parents and their in-laws. In Table 5, we compared the correlations of children with the correlations of their parents. With the exception of the comparison of father vs. son correlation over the good provider trait where the correlation was stronger in fathers than in sons, the correlation coefficients were not significant. These findings indicate that, in general, parents want their in-laws to be as similar to their children as their children want their spouses to be with them.

Table 5.

Comparisons of the Correlations Coefficients of Mothers With Their Children and Fathers With Their Children.

	Mothers vs daughters	Mothers vs sons	Fathers vs daughters	Fathers vs sons
Desirable traits	p-value	p-value	p-value	p-value
Good looks	.505	.510	1.00	.309
Good provider	.821	.319	.823	.023
Good economic prospects	1.00	.722	.732	.943
Good family background	.227	.373	.275	.877

Discussion

Using data from a sample of families in China, we found that mothers and fathers tended to agree on how they perceived their children across four desirable traits, namely good looks, good providers, good economic prospects, and good family background. Additionally, both parents evaluated their children, scoring them higher in these traits than their children scored themselves. Furthermore, parents expressed a preference for sons- and daughters-in-law who were similar to their children, particularly with regard to family background. Additionally, mothers and fathers were in agreement on the degree of similarity they desired between their children and their in-laws. Finally, parents desired as much similarity between their children and their in-laws as their children desired between themselves and their spouses.

Consistent with the findings of previous research (Wang & Apostolou, 2017b), we observed that fathers and mothers generally agreed on their perceptions of their children. While there was considerable overlap in their evaluations, there was also a significant degree of discrepancy. Nevertheless, these discrepancies did not follow a systematic pattern, indicating that they were stochastic. On the other hand, we found that parents tended to perceive their children as scoring higher in desirable traits than their children perceived themselves. This finding aligns with the hypothesis that parents tend to overrate their children across different dimensions, facilitating the view of their children as a good investment and motivating them to invest in them. Previous research supports this argument; for example, in two correlational studies, parents rated the extent to which trait adjectives (e.g., “sincere,” “dishonest”) described their child and “the average child of the same age” (Cohen & Fowers, 2004; Wenger & Fowers, 2008). The results indicated that a majority of parents rated their own child as having more favorable and fewer unfavorable traits than the average child.

It is crucial to emphasize at this point that in this hypothesis, parents tend to overrate rather than completely distort the positive traits of their children. That is, their evaluations would be, to some degree, objective. For example, if their children are physically unattractive, parents would not see them as very physically attractive, but rather as not very unattractive. This is necessary because if parents were to completely distort how they perceive their children, they would not be able to choose in-laws who are similar to their daughters and sons. Moreover, not all children can use parental investment equally well (Šaffa et al., 2021), meaning that parents need to objectively assess their children to some extent to allocate parental investment more optimally. Also consistent with the findings of previous research (Wang & Apostolou, 2017b), we found that parents preferred their children to be to some degree similar to their prospective in-laws.

Moreover, fathers and mothers preferred comparable levels of similarity in their children with their in-laws, indicating that parents are in agreement on this dimension. Additionally, our prediction that children would prefer their spouses to be more similar to them than their parents would prefer their in-laws to be with their daughters and sons was not supported. Thus, our data indicate that similarity does not constitute an area of disagreement over mating between parents and their children. Nevertheless, we need to consider that our study was confined only to four desirable traits, so future studies need to examine if there is a disagreement over similarity using a more inclusive list of desirable traits.

The limited number of desirable traits is not the only limitation of our study. In particular, although our total sample size was generally good, the subsample of parents-sons was relatively small, so power issues may arise. Moreover, we employed data from self-report instruments, which are subject to several biases, including participants not giving accurate answers. Additionally, we employed a nonprobability sample, so our findings may not readily generalize to the population. Furthermore, our study was confined to the Chinese cultural context, so its findings may not readily apply to other cultural contexts.

Mate choice is usually seen as involving two parties, namely, a man and a woman, but in reality, it involves four parties, namely, a man and his parents, and a woman and her parents. This is actually a uniqueness to our species, as there is no other species on the planet where parents are involved in the mate choices of their children. A system that involves four parties instead of two is more complex to understand. For instance, individuals usually enter into intimate relationships with partners who are similar to them. This is an outcome of themselves preferring individuals who are similar to them plus their parents preferring in-laws who are similar to their children. In turn, this raises several questions, including whether parents and children agree on how much similarity they want, whether parents agree among themselves on how much similarity they want, whether parents agree among themselves on how they assess their children, and whether parents see their children as their children see themselves in desirable traits. The current research has attempted to address these questions; still, given its complexity, considerable more research is necessary for understanding this phenomenon.