Why do body scan meditations exclude the genitals?

So I've been doing these body scans for a while now and I noticed they never mention the genitals. This is a bit odd to me being that we interact with and notice our genitalia much more often then say, the backs of the hands or earlobes, which I hear mentioned all the time. Is this exclusion just because thinking about genetalia makes some people uncomfortable or is considered sinful to some? It just seems weird to me that this major part of our bodies that has a huge part in our health would be totally disregared in a meditation which has the goal of honoring, noticing and respecting our bodies.