Big sister syndrome: what science tells us about the place in siblings

Big sister syndrome: what science tells us about the place in siblings

Among siblings, eldest daughters often inherit a greater mental load than eldest sons. But this place would also make them mature more quickly, announces an American study carried out over 15 years.

It’s not fair, but it’s a fact: eldest daughters in our families often do more than sons. More mental load, more daily help, more care for little brothers and sisters… But what we know little about and what a study from the University of California reveals to us is that these same older girls have tend to also mature more quickly, and develop signs of puberty earlier. Which would not be linked to chance.

Maturity of older daughters: a link found with prenatal stress

The researchers followed Californian families for 15 years, from the mother’s pregnancy until their child’s adolescence. They measured the mother’s prenatal stress levels at five stages of pregnancy: she simply had to indicate on a scale whether she felt depressed, anxious, etc. The researchers then evaluated certain criteria including signs of early puberty, in the children, who were half girls and half boys. These superficial physical changes would indeed seem to be correlated with a certain emotional maturity.

Stressed mother expects more from her daughter

For researchers, this correlation between the mother’s prenatal stress and the precocity of the first borns would undoubtedly be a story of “survival” which then takes place.

“When times are tough and mothers are stressed during pregnancy, it is in the mother’s interest for her daughter to mature socially more quickly. This gives mothers help in the nest earlier, in order to keep their offspring in life in difficult environments”explained Jennifer Hahn-Holbrook, one of the co-authors of the study, to HuffPost.

Oddly, this link was not found among the eldest sons who seem to be sheltered from this type of somewhat forced mental load. But not everything can be based on science: Jennifer Hahn-Holbrook’s hypothesis would be that older boys are asked less to take care of children born after him, for example, in such a cultural way.

Older girls are therefore a little “programmed” to mature more quickly, especially if their mother has had a somewhat stressful pregnancy. But this would not only have disadvantages: other studies also suggest that these girls who grow up faster are also those who would be more likely to succeed in life or access higher positions.