It’s a well-known truism that people generally have an inner circle of about 5 individuals which make up about 50% of their social interaction. This paper analyzes the gender breakdown across age of those relationships. It’s important to note, however, that this paper’s dataset was simply anonymized communications from a large European telecom, so the research treats spouses, children, relatives, and friends all the same. The study used frequency of contact as a proxy for emotional closeness.
The authors find that, starting in the early twenties most people’s “best friend” is an individual of the opposite gender, and as people grow older, the chance of them being someone of the same gender very slowly starts to even out. This shift to opposite gender relationships happens slightly earlier in females (possibly due to an earlier onset of puberty?).
In contrast, the “second best friend” shows a strong same-sex preference in early adult-hood and then a sharp reversal in middle age. This makes me think that the study was capturing individuals’ significant others as the “best friend” and then a close friend from early childhood (or maybe just a plain platonic one) as the “second best friend”.
The paper also showed that women appear to be more in contact with their adult children, and that older adult women seem to show a slight preference for communicating with their female offspring over their male offspring. Older adult men showed no such preference. It should also be noted that throughout the study women seem to switch who their “best friend” is far more sharply than men do.