[Serious] Literal and Not Literal

[Acrobat]

The genes you and your sister have in common (and most of the ones you don't ) are copies of your parent's genes. There are no extant 'original genes' to survive. It's all copying and copy errors. Genes don't care about anything, but it's a brute fact that if your sister survives to have children, some copies of your genes will be passed on, even if you die before reproducing. If instinctive family bonding influenced by a complex of genes increases the odds of more copies of those genes being passed on, the predisposition to bond with close family members will be passed on. The same is true if bonding in bands or larger groups conveys similar benefits. It's information, and it's math, but it has a concrete expression in phenotypes.

The predisposition to bonding. 

There's no reason to believe we developed separate bonding mechanisms for family, for community, friends, or even with my dog. Closeness seems to be good term for what influences our bonding.

It's not instinctive family bonding, but more like instinctive bonding with those close to us, even if they are other animals. Families just benefit from the fact that they tend to be the people we're closest to, from conception.