For me it is more the other way round. The older I get the less understanding I have for them. As a teenager I got along perfectly with them but now that I am almost 40 I realize that they were pretty shitty parents. Especially when I realize what they did to my siblings.
Edit: To expand I have more sympathy with my mother because I know of some of her traumas growing up. But I have a harder time to excuse my father.