Sunday was Father's Day.

If you forgot, now is a good time to run to the phone and call your dad to apologize -- or, get on Twitter and tweet with a belated #happyfathersday. (We'll wait).

OK, back?

In a striking coincidence with the annual paternal celebration, a recent study has found that the number of American stay-at-home dads has increased two-fold in the past 10 years. It seems that in 2001, there was an estimated 81,000 fathers in the USA who were the primary childcare givers in their homes. In 2011, the number jumped to more than twice that -- with 176,000 dads staying at home with their kids.

While a lot of people assume that the recession had some involvement with the jump in numbers, researchers actually credit more the society shift of gender roles as the main cause of the increase. Still, even the high numbers of dads taking care of children only accounts for 3.4% of parents who stay home with the kids.

You have no idea how hard it was to write this without making a lame joke referencing the 1980s Michael Keaton classic comedy, "Mr. Mom."