Whether or not Hoid is capable of having children has been RAFOed in the past. Both of them have some degree of future sense, maybe, which could be spiritual genetics. December's father was described as having "the charm of a sonnet but the morals of a limerick", which doesn't seem massively far off Hoid to me. They've also both got apparent resurrection talents, although these don't seem to work the same way, which could again be spiritual genetics - like a passing down of the Dawnshard effects? This could also explain why December didn't get ill. Most of my argument is just that their magics seem similar.
As I said, it's a very vague theory and I don't have a lot of evidence to support it.