For example, most mammals are either monogamous or polygamous. But as every poet or divorce attorney will tell you, humans are confused - After all, we have monogamy, polygamy, polyandry, celibacy, and so on. In terms of the most unique thing we do socially, my vote goes to something we invented alongside cities - we have lots of anonymous interactions and interactions with strangers. That has shaped us enormously.

How much you groom somebody else is more important than who grooms you.

Oxytocin is lauded for how it promotes warmth, generosity, social bonding, cooperation, trust, and compassion.

To out-group-members, oxytocin makes you crappier - less cooperative and more preemptively aggressive. It's not the luv hormone. It's the in-group parochialism/xenophobia hormone.

Importantly, rather than promoting aggression, testosterone promotes whatever is needed to maintain status when challenged.

Hormones influencing the sensitivity of the person to environmental stimuli.

Genes are rarely about inevitability, especially when it comes to humans, the brain, or behavior. They're about vulnerability, propensities, tendencies.