Accepting Someone Else's "Mazal Tov"
My father-in-law, Rav Avraham Moshe Babad zt"l, would say that we often find people being congratulated for accomplishments that are not their own. For example, a wagon driver is cheered for having reached his destination in time, as if it was his expert steering that did the job, and not the hard work of the unsung horses. So too, men are wished a hearty "mazal tov" by their friends on the birth of their children, and they smile and take credit as if they were involved in all the hard work. The real mazal tov belongs to the mother, who suffered for nine months to bring the baby into the world.