Each child after the first born is slightly less bright as they have to 'share' parents, revealed a new study by the Leipzig University in Germany.
Scientists also suggest that having your parents' undivided attention means you end up learning more, which benefits the eldest child. However, in a two-child family the eldest won't necessarily dominate. They have a six in ten chance of a higher IQ, so their younger relatives still have a strong chance of overtaking them.
‘Children who have their parents' undivided attention end up learning more, which benefits the eldest child. They display heightened intelligence and an increased perception of their brain power.’
As well as demonstrating a heightened intelligence, older children also displayed an increased perception of their brain power.
The study is published in the Proceedings of the National Academy of Sciences.