Heavier Twin May Have More Behavior Problems, Study Finds
Twins who were at least 20 percent heavier than their sibling at birth were more likely to have conduct problems by the time they were 3 or 4 years old, an article published in the May issue of the Archives of Pediatric and Adolescent Medicine, says. That finding was more true of fraternal twins than of identical twins.
Researchers at Hadassah Hebrew University Hospital in Jerusalem identified 112 families with twins born at unequal weights in 2004 and 2005. They gave the mothers a widely used screening questionnaire in which the mother rated the applicability of statements to her child, including things such as "often fights with other children or bullies them," "often lies and cheats," and items referring to stealing, temper tantrums and defiance.
According to their mothers, the heavier twin had more conduct problems in 41 percent of twin pairs; that was true of the lighter twin in only 21 percent of twin pairs.
The authors of the study speculate that larger twins may become more aggressive because they are able to physically dominate their smaller sibling. Furthermore, smaller twins are often hospitalized for longer, and that may lead mothers to "invest more time, effort and emotional resources in the weaker, smaller twin, possibly increasing the larger twin's likelihood for developing conduct problems," the article says.
Related: Are Matching Twin Names Too Cheesy?
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