Is it possible that Mothers of sons behave differently to Mothers of daughters, though, and that's why so many MILs on here (where there's presumably a higher number of female posters) are Mums to men?
I have to admit my MIL is the overbearing Mother-to-adored-son cliche who felt that nobody was good enough. It is what it is; if you want to 'hold on' to your darling babies despite them being fully formed adults, you're unlikely to make yourself popular with in-laws. My Mum always said you give your children the roots to stand tall and the wings to fly high; she's never once attempted to direct DH and I with our marriage, our parenting, our lives generally. And because of that, we have a great relationship and she and her DH are a very positive influence on our lives. They're present, they're helpful, they adore the grandchildren but they also live their lives to suit themselves.
MIL on the other hand is quite controlling and manipulative, so watching DH 'break away' if you like over the last few years has been hard. She loves him, he loves her, but their relationship was so unbalanced that once we began having our own family MIL felt as though she'd lost him and had all sorts of dramatic temper tantrums to try and ensure she kept her place as number one in his life. Of course, DH has a wife and children who he has to prioritise and the whole thing is just incredibly sad for them both; neither is able to have a direct, honest conversation with the other, it's all resentment swept under the carpet. I can't help but think it's such a waste of both of their time. At a family get-together a while back she told my Mum that without her children she has nothing worth living for. My Mum was horrified, not really understanding just how over-invested MIL was until that point.
As Mother to two small boys I'm determined to be more like my Mum and love them enough to cherish whoever they decide to spend their lives with, and simply be there when they need me.