There is a natural tendency (or lack of it) towards being a social person. I have two kids, a boy and a girl (6.5 and 2.5). They are both smart for their age and very verbal, and of course raised in the same home, and share most of their genetic traits.
But you can already see that my son is a geek (well, what might "save" him socially is that he's tall and athletic), and my daughter is probably going to be popular. She simply has a better natural grasp of how people interact, and is much more interested in interactions, than say, imagination games. They are both very charming and outgoing, but you can already tell she has or will have better social skills.
There is probably also a snowball effect at play, too - if you have a tendency to be social, you might develop stronger social skills, etc.
But you can already see that my son is a geek (well, what might "save" him socially is that he's tall and athletic), and my daughter is probably going to be popular. She simply has a better natural grasp of how people interact, and is much more interested in interactions, than say, imagination games. They are both very charming and outgoing, but you can already tell she has or will have better social skills.
There is probably also a snowball effect at play, too - if you have a tendency to be social, you might develop stronger social skills, etc.