"I'd have to explain what's going on to my kids."
That's the reason some people gave when asked why they might have a problem with two women kissing in public.
To them I say, "That's the job. You're parents."
One constant inquiry of my oldest is on the subject of death. We drive by a number of cemeteries out here in the 'Burbs. Philip will often comment, "That's Heaven. Right, Daddy?" Or, "That's where we go when we die. Right, Daddy?" I try to tell him that our soul goes up in the sky (I can't avoid my Catholic upbringing entirely) to heaven, and that the cemetery is where we put your body after you die. Not a great answer. Not the only answer, but the best I can do.
I also don't avoid the answer, "I don't know." This isn't much of an answer, but I want to encourage him to find the answers himself. These answers can often be found in books. Books contain the whole knowledge that we have accumulated as humans. If you have a question and no answer there is a good chance a book will have the answer you seek.
I haven't figured it all out, but it seems that avoiding subjects, within reason of course, is the wrong choice to make as a parent.