The herbivore (I assume that's what you meant), 草食系男子 has little to do with "not wanting family" and more to do with men that are not keen to approach / take initiative towards women. Usually not just because of shyness but because relationships are very very low in their priority list.
絶食系(roughly translated to "fastivore", fasting) are probably the one you're referring to.
The statistics that says 40-60% of 30s year old males have never been in a relationship is probably more from this attitude.
Even more so because Japan does not encourage immigration. But I think in the long run this will be better for Japan. It will probably be the first modern economy that will learn to deal with a shrinking workforce.
絶食系(roughly translated to "fastivore", fasting) are probably the one you're referring to.
The statistics that says 40-60% of 30s year old males have never been in a relationship is probably more from this attitude.