Social functioning among girls with fragile X or Turner syndrome and their sisters.

The team compared girls with fragile X or Turner syndrome to their own sisters. They asked: do the girls with the syndromes show more social and attention problems?

Using sister controls removed most family differences. Any gap that stayed could point to biology, not parenting style.

Girls with fragile X or Turner syndrome had more social and attention trouble than their sisters. The problems looked similar in both syndromes.

Because sisters share the same home, the authors say the gap is likely rooted in the genes or brain, not in how Mom and Dad behave.

Martin et al. (1997) saw more autistic-like actions in fragile-X girls one year earlier. The new sister design backs up that link and shows the cause is not just family style.

Kuo et al. (2002) later found family environment predicts IQ in typical girls but adds nothing for fragile-X girls. This matches the idea that biology, not home life, drives both thinking and social gaps.

Lesniak-Karpiak et al. (2003) tried to repeat the social finding with a short role-play. Only a few behaviors differed, so they called the result "mixed." The gap is real, but you need longer or richer tasks to see it.

Casey et al. (2009) tracked young fragile-X girls over time. Even mild autistic signs foretold slower growth. The 1998 snapshot and the 2009 trajectory together say: watch social skills early and often.

If social problems come from biology, don’t blame parents. Spend your energy on skills training, peer practice, and anxiety management. Screen sisters too—some may carry the gene and show subtle signs. Track progress every few months; the deficit can widen as girls get older.