I'm waaay waaay softer with DS (12 yrs in between), even though I feel my parenting ideals are much the same all the same.

It's just that DS was a very difficult unsettled baby and it took so much of our energy to keep him settled and relatively happy that I don't feel like I had the time to 'teach' him. A lot of things I just had to let go and unfortunately I feel it's showing a bit. DS needs really firm boundaries and it's only now (he's 5, dd 3), that he is older than I have the time and clarity of mind to do so .

But that's just my experience. I daresay that many of us relax somewhat in our parenting with the later children because you realize how to choose your battles and not sweat the small stuff so much.