3. Institute for Social and Economic Research, University of Essex
Date: 2006
-model: 1.503 families (3, 532 individuals)
This study of about 1,500 families showed that 16% of first born siblings who had a four year or lower age gap with the next sibling(s) were more ambitious. This study believes the best age gap is about four years and comes in at number three on our list of easiest age gap between babies: 5 research studies.
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