Older Brothers Can Cause Stunted Growth in Their Younger Siblings

Sibling rivalries, especially between two brothers, are not uncommon. A new study suggests that having an older brother can make it even more likely for the younger males in a family to be about an inch shorter than the average height due to stunted growth. It seems that sibling rivalry starts in the womb when an older brother stunts growth in male children that will later be conceived.

One of the studies presented at the BA festival of science followed the children of 14,000 families and showed that the children in the larger families were more likely to be shorter on average, according to the BBC. Scientists are not sure why the stunted growth seems to be the rule rather than the exception in larger families, but it is known that children who come from larger family groups tend to do less well in school.

The study showed that both genders of younger siblings could be affected by stunted growth, but male siblings born after the oldest male tend to be more affected by the stunted growth problem. The reasons for this may be that boys are more demanding both in the womb and being raised which takes its toll on the mother. The oldest child of the mother is unaffected, but children coming later to their parents will show signs of either stunted growth or the dwindling of resources such as time and the affection of the parents available.

The beginning of sibling rivalry begins when the mother first gets pregnant as later children will make up less time and effort on the part of the parents available to every child. One possible explanation for stunted growth is that after each pregnancy the mother puts on weight and her body is less able to properly handle blood sugar. The study did not do research into whether larger families tended to be happier.