pinkyBear: I think you are working for the wrong company. Where I am, it is the young singles without kids that leave on time more so than the (by now) grey-bearded ones.
Squash, swimming, hangen', chillen', nights out, telly, and 'stuff' seems to be more of a draw for the young guns than family is for the older guns. The family guys just get on and deal with their commitments, juggle well, work at home if necessary when the kids are in bed, and yes, they are well looked after. Any young gun that sticks his head above the rest gets the lift he deserves. Attitude is rewarded as much as effort.
Talk to your manager, find a solution, or move on - but don't lose the conscientiousness. Don't look for an easy life elsewhere. Look for a place that appreciates your conscientiousness. They are out there.