Yep, hobbies is the place for things like this. Just keep in mind that once you put this information on your ERAS application it makes it fair game for an interviewer to ask questions related to your family, which otherwise might be considered illegal. If you truly want to discuss this information in an interview setting and feel that any answer related to your family would not be seen in a negative light, this may not matter to you... but just worth considering before you put this on there.