... [Politicians such as Uhuru Kenyatta insist that homosexuality isn’t “really” African.]  Never mind that the continent has a long history of same-sex love, going back many centuries. Homosexuality wasn’t banned until the colonial era, when missionaries brought anti-gay attitudes and laws to Africa.

But as Western countries began to decriminalize homosexuality, after the Second World War, many new African nations stepped up their campaigns against it. Homosexuality isn’t a legacy of colonialism, as Africans often charge; instead, homophobia is.

And legacies can change. During his Kenya visit, Mr. Obama denounced forced marriage of young girls and other patriarchal practices on the continent. “Treating women and girls as second-class citizens, those are bad traditions,” he said. “They need to change.”

I didn’t hear anyone suggest that those traditions are timeless features of African culture. They’re shifting, as more women get access to education, health care and employment.

So are attitudes about gay people, although the rate of change is slower. But one day, I predict, the eloquent appeal last weekend by “the first Kenyan-American president” – as Mr. Obama proudly called himself – will be seen as a landmark for equality in Africa and around the world.

“If somebody is a law-abiding citizen … the idea that they are going to be treated differently or abused because of who they love is wrong,” Mr. Obama declared. “Full stop.”

Homophobia won’t stop in Africa so long as Africans persist in seeing homosexuality as alien to the continent. I’m glad America has a president of African descent, to remind them that it isn’t.