don't confus Causation with Correlation
Yes there may be a correlation between a fatass and gyno but that doesn't mean that
"If you are fat, you have a higher chance to get gyno"
it means:
"being fat MAY increase risk of gyno, OR what causes someone to be fat may cause someone to be at higher risk of getting gyno"
Based on some basic endochrinology one might assume that a common cause for having extra fat is being overly sensitive to estrogen due to issues with beta 2 receptors. If this is the case, someone with this problem will be more likely to gain/hold fat AND most likely also be sensitive to gyno . . .
However this same person may have their diet very much in check and be at 10% bf and look great but toss in some extra estrogen from somewhere and they get gyno easily.