By "social circle" I did not mean people I go out for drinks with - I'd call those "friends". I simply meant people I have something in common with, share the same values with, people I can relate to. If the candidate is older with kids (assuming I'm younger) - he/she should be someone I want to become in the future, someone I respect, someone I'd learn from. Race, gender, age, even education - does not really matter - as long as I'm genuinely interested in that person and feel like I'd enjoy working with them. After many years of interviewing and hiring at various startups this is more important to me than technical skills. Skills could be learned, personalities usually don't change.
