In a post for the New York Times’s Campaign Stops blog, Kenji Yoshino zeroed in on an aspect of President Obama’s support for same-sex marriage that hasn’t gotten nearly enough attention: the affirmation of gay men and lesbians as parents. And there are plenty of them. According to an October 2011 report from the Center for American Progress, Movement Advancement Project and the Family Equality Council, about 2 million children are being raised in households headed by same-sex parents. Unfortunately, because of the so-called Defense of Marriage Act, those families are being short changed by the same federal government they pay taxes to.

If you want to know why marriage equality matters, you need only look at these two charts from that October 2011 report. One shows the increased tax burden. The other illustrates the added costs same-sex couples must bear just to hold their families together.

(Center for American Progress)

Steve earns $40,000. William makes $5,000. Because of DOMA, they are barred from filing jointly. And various child tax credits are denied same-sex couples if the primary earner, such as Steve, is not legally recognized as a child’s parent.

As a result, Steve is only able to take $9,350 in deductions, which brings his taxable income to $30,650. Since he is not recognized as a legal parent of their two children because they live in a state that doesn’t permit gay couples to adopt, Steve can’t take advantage of the child credits the married heterosexual couple can. Because William is not legally recognized as a spouse, Steve can’t deduct the $1,000 he pays in college tuition for him. This leaves Steve with a tax liability of $4,175. William is the legal parent of their children, so he gets a larger dependent exemption and gets a $2,000 child credit. In the end, he gets a $2,010 refund. All told, Steve and William owe $2,165 in taxes.

(Center for American Progres)

Jennifer can’t extend her health insurance to Katie or their children. Because they cannot file jointly (thanks to DOMA) they lose out on child tax credits and other child-related deductions. And because Katie and their children are legal strangers to Jennifer when she unexpectedly dies, they are denied Social Security survivor benefits. All of these inequities and more add up to an additional financial burden of $219,262 over 18 years.

In his interview with Robin Roberts, the president discussed talking with his daughters about their friends and parents, some of whom are same-sex couples. “[I]t wouldn’t dawn on them that somehow their friends’ parents would be treated differently. It doesn’t make sense to them,” he said. “And — and frankly — that’s the kind of thing that prompts a change of perspective. You know, not wanting to somehow explain to your child why somebody should be treated differently, when it comes to the eyes of the law.”

Obama merely expressed his personal views in favor of marriage equality. But his words will have profound impact on LGBT families. In the short term, they are a psychological boost. In the long run they will be the catalyst for legal, societal and financial equity.