Table 3.
Results for individual-level and co-twin analyses.
| Analysis type | (95% CI) | P | ΔR2 | ||
|---|---|---|---|---|---|
| ACA | Academic performance | Individual | 0.026 (−0.034, 0.086) | 0.39 | 0.0252 |
| Co-twin | 0.135 (0.014, 0.256) | 0.029 | 0.0533 | ||
| Co-twin MZ | 0.361 (0.107, 0.615) | 0.006 | 0.0449 | ||
| SUB | Substance use | Individual | 0.257 (0.188, 0.326) | < 0.001 | 0.0178 |
| Co-twin | 0.139 (0.001,0.277) | 0.049 | 0.0019 | ||
| Co-twin MZ | 0.083 (−0.159, 0.325) | 0.50 | 0.0010 | ||
| EXT | Externalizing problems | Individual | 0.217 (0.148, 0.287) | < 0.001 | 0.0113 |
| Co-twin | 0.099 (−0.027, 0.226) | 0.13 | 0.0004 | ||
| Co-Twin MZ | −0.164 (−0.440, 0.113) | 0.25 | 0.0028 | ||
| INT | Parent-reported internalizing | Individual | −0.087 (−0.160, −0.013) | 0.021 | 0.0018 |
| Co-twin | −0.033 (−0.151, 0.085) | 0.59 | −0.0011 | ||
| Co-twin MZ | −0.063 (−0.272, 0.146) | 0.55 | 0.0007 | ||
| Teacher-reported internalizing | Individual | −0.162 (−0.240, −0.084) | < 0.001 | 0.0051 | |
| Co-twin | −0.067 (−0.208, 0.075) | 0.36 | −0.0007 | ||
| Co-Twin MZ | −0.030 (−0.316, 0.257) | 0.84 | 0.0001 | ||
| PEER ENV | Peer deviance | Individual | 0.167 (0.116, 0.219) | < 0.001 | 0.0120 |
| Co-twin | 0.051 (−0.040, 0.142) | 0.27 | 0.0010 | ||
| Co-twin MZ | 0.022 (−0.115, 0.159) | 0.75 | 0.0002 | ||
| Sports involvement | Individual | 0.187 (0.105, 0.269) | < 0.001 | 0.0060 | |
| Co-twin | 0.100 (−0.047, 0.248) | 0.18 | 0.0014 | ||
| Co-twin MZ | 0.121 (−0.142, 0.385) | 0.37 | 0.0017 | ||
| Time with friends | Individual | 0.264 (0.193, 0.334) | < 0.001 | 0.0157 | |
| Co-twin | 0.132 (0.000, 0.264) | 0.051 | 0.0029 | ||
| Co-twin MZ | 0.039 (−0.180, 0.259) | 0.73 | 0.0003 | ||
| HEA | Age 12 sleeping difficulties | Individual | 0.079 (0.013, 0.146) | 0.019 | −0.0003 |
| Co-twin | 0.066 (−0.028, 0.160) | 0.17 | −0.0045 | ||
| Co-twin MZ | −0.030 (−0.165, 0.105) | 0.66 | 0.0005 | ||
| Age 14 sleeping difficulties | Individual | 0.102 (0.044, 0.160) | 0.001 | 0.0034 | |
| Co-twin | 0.070 (−0.009, 0.149) | 0.084 | −0.0016 | ||
| Co-twin MZ | −0.021 (−0.130, 0.089) | 0.71 | 0.0003 | ||
| Perceived health | Individual | −0.025 (−0.085, 0.036) | 0.42 | 0.0019 | |
| Co-twin | −0.021 (−0.110, 0.068) | 0.65 | −0.0008 | ||
| Co-twin MZ | −0.025 (−0.162, 0.113) | 0.73 | 0.0003 | ||
| Physical activity | Individual | 0.003 (−0.059, 0.065) | 0.92 | 0.0012 | |
| Co-twin | 0.013 (−0.088, 0.113) | 0.80 | −0.0008 | ||
| Co-twin MZ | −0.070 (−0.236, 0.095) | 0.40 | 0.0015 | ||
| PARENTS | Age 12 relationship quality | Individual | −0.117 (−0.188, −0.045) | 0.001 | 0.0030 |
| Co-twin | −0.036 (−0.178, 0.107) | 0.62 | 0.0002 | ||
| Co-twin MZ | 0.079 (−0.129, 0.286) | 0.46 | 0.0011 | ||
| Age 14 relationship quality | Individual | −0.198 (−0.267, −0.129) | < 0.001 | 0.0093 | |
| Co-twin | −0.067 (−0.196, 0.063) | 0.31 | 0.0007 | ||
| Co-twin MZ | 0.026 (−0.168, 0.219) | 0.80 | 0.0001 | ||
| PARENTS | Parental discipline | Individual | 0.110 (0.040, 0.181) | 0.002 | 0.0028 |
| Co-twin | 0.000 (−0.122, 0.123) | 0.99 | 0.0000 | ||
| Co-twin MZ | −0.034 (−0.201, 0.134) | 0.69 | 0.0003 | ||
| Time with parents | Individual | −0.086 (−0.149, −0.023) | 0.008 | 0.0021 | |
| Co-twin | −0.014 (−0.124, 0.096) | 0.81 | 0.0000 | ||
| Co-twin MZ | −0.164 (−0.328, 0.000) | 0.051 | 0.0077 | ||
| UNCAT | Age 12 pubertal development | Individual | 0.032 (−0.032, 0.095) | 0.33 | 0.0008 |
| Co-twin | −0.010 (−0.126, 0.107) | 0.87 | −0.0040 | ||
| Co-twin MZ | 0.099 (−0.106, 0.304) | 0.35 | 0.0020 | ||
| Age 14 pubertal development | Individual | −0.018 (−0.081, 0.045) | 0.57 | 0.0004 | |
| Co-twin | −0.078 (−0.179, 0.022) | 0.13 | −0.0021 | ||
| Co-twin MZ | −0.096 (−0.279, 0.087) | 0.30 | 0.0024 | ||
| Alcohol expectancies | Individual | 0.292 (0.178, 0.405) | < 0.001 | 0.0310 | |
| Co-twin | 0.308 (0.021, 0.594) | 0.037 | 0.0314 | ||
| Co-twin MZ | 0.286 (−0.223, 0.795) | 0.28 | 0.0181 | ||
| Difficulty of life events | Individual | 0.090 (0.021, 0.159) | 0.011 | −0.0063 | |
| Co-Twin | −0.013 (−0.134, 0.109) | 0.84 | −0.0193 | ||
| Co-twin MZ | 0.010 (−0.181, 0.202) | 0.92 | 0.0000 | ||
| Life events | Individual | 0.054 (−0.011, 0.118) | 0.10 | 0.0021 | |
| Co-twin | −0.056 (−0.178, 0.067) | 0.38 | −0.0005 | ||
| Co-twin MZ | −0.118 (−0.311, 0.075) | 0.23 | 0.0031 |
ΔR2 refers to the change in variance explained from a sex-only baseline model. ACA = academic performance; SUB = early adolescent substance use; EXT = externalizing problems; INT = internalizing problems; PEER ENV = peer environment; HEA = physical health; PARENTS = relationship with parents; UNCAT = uncategorized predictors; CI = confidence interval’ MZ = monozygotic.