system
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human
[Dungeons and Dragons] With Aasimar being relatively common, just how and when does all this intercourse between angels and mortals occur?

Do angels commonly visit the mortal world in disguise and go out on the town? Or do they visit their god's faithful for the express purpose of breeding angel/mortal offspring? Do angels actually fall in love with really amazing clerics and paladins? And I lean towards assuming the mortal in the situation is almost always female, but will a lady angel sometimes stay on the prime material plane long enough to complete a pregnancy?
gpt
Aasimar aren't that common. 

One of the guides states "Aasimar could live for the whole of their life without ever meeting another of their kind and, as such, were resigned to living amongst other races".

Aasimar also aren't always the direct results between celestials and mortals, more like descendants. IIRC it's uncommon but not unheard of for two humans to give birth to an aasimar because one or both had an angel as an ancestor.