In another study, researchers found mommy's boys are less likely to suffer from poor mental health or unpopularity at school. Picture: PxHere

London - Firstborn children are more sociable and "emotionally available" to their mothers than those born second, a study reveals.

When 55 moms were observed playing with their first or second child at 20 months, the firstborns were more willing to respond to their mother’s suggestions and displayed more enjoyment playing with her.

They were also more sociable with other adults. Dr Diane Putnick, who co-led the US study from Eunice Kennedy Shriver national Institute of Child Health and Human Development, in Maryland, said: "Firstborn children may be more sociable and emotionally available to their mothers because they have the benefit of years of their parents’ undivided attention.

"Perhaps this concentrated time with mothers early on leads firstborn children to develop better social skills in relationships with adults." The study is published in the journal Social Development.

In another study, researchers found mommy's boys are less likely to suffer from poor mental health or unpopularity at school.

And the same is true for daddy’s girls, who enjoy a similar lift in their self-esteem and confidence.

The study by the Marriage Foundation concluded that boys and girls who are close to their parent of the opposite sex fare better at coping with teenage life.

Boys deemed "extremely close" to their mothers at 14 are 41 percent less likely to have mental health problems, the research found. And girls close to their fathers are 44 percent less likely to suffer emotional problems or have trouble with their peers.

While boys are happier when their parents are married, girls are more reassured by their parents demonstrating a high-quality relationship.