Table 3. The age-adjusted genetic, shared and non-shared (individual specific) environmental influences on variance of total serum 25-hydroxyvitamin D and 25-hydroxyvitamin D3 levels (95% CI) during summer and winter seasons among Swedish adult twins.
| Model | Proportion of variance explained by genetic influence (A) | Proportion of variance explained by shared environmental influence (C) | Proportion of variance explained by non-shared environmental influence (E) | −2 log-likelihood | P value for difference from ACE model |
| Summer season n = 148 | |||||
| Total 25-hydroxyvitamin D | |||||
| ACE | 0.48 (0.00–0.85) | 0.25 (0.00–0.64) | 0.26 (0.14–0.51) | 1342.48 | Ref |
| AE | 0.74 (0.56–0.84) | - | 0.26 (0.16–0.44) | 1344.22 | 0.19 |
| CE | - | 0.57 (0.39–0.70) | 0.43 (0.30–0.61) | 1345.46 | 0.08 |
| 25-hydroxyvitamin D3 | |||||
| ACE | 0.48 (0.00–0.85) | 0.26 (0.00–0.64) | 0.26 (0.14–0.50) | 1342.83 | Ref |
| AE | 0.74 (0.57–0.85) | - | 0.26 (0.15–0.43) | 1344.46 | 0.20 |
| CE | - | 0.57 (0.40–0.71) | 0.43 (0.29–0.60) | 1345.92 | 0.08 |
| Winter season n = 56 | |||||
| Total 25-hydroxyvitamin D | |||||
| ACE | 0.00 (0.00–0.77) | 0.72 (0.00–0.86) | 0.28 (0.14–0.52) | 485.00 | Ref |
| AE | 0.73 (0.48–0.86) | - | 0.27 (0.14–0.52) | 489.22 | 0.04 |
| CE | - | 0.72 (0.48–0.86) | 0.28 (0.14–0.52) | 485.00 | 1.00 |
| 25-hydroxyvitamin D3 | |||||
| ACE | 0.00 (0.00–0.63) | 0.73 (0.10–0.86) | 0.27 (0.13–0.49) | 484.10 | Ref |
| AE | 0.73 (0.47–0.86) | - | 0.27 (0.14–0.53) | 489.15 | 0.02 |
| CE | - | 0.73 (0.51–0.86) | 0.27 (0.14–0.49) | 484.10 | 1.00 |