The President's dark skin comes from his father who was from Africa where slavery is still practiced.
Something she never mentions and might never have occurred to her - when she wakes up in a house built by slaves, she's sharing a bed with the descendant of slave-owners. Barack's white mother's family owned slaves. This came out in 2008 but was quickly forgotten after Oprah said that she'd be honored if Obama's ancestors had owned her ancestors.
It would be much more accurate for Michelle to say that every day she wakes up in a house that has a facade built by slaves. But that doesn't have much ring to it.
More important is the rebuild that happened under President Truman. The original building had deteriorated by then and was in danger of collapse. Truman had the entire building gutted. The facade was saved but everything else was replaced with a modern steel-girder building. The White House was also enlarged significantly with wings and underground offices.
What it usually skipped is that the current building is *not* the original White House. It has been rebuilt twice. The first time was after the British burned it during the War of 1812. It was reduced to a mere shell. None of the fact-checks I've seen talk about that rebuild.
Claims that slaves quarried the stone for the White House seem to be the strongest. Possibly slaves also worked under the direction of master stone carvers in building the structure.
On a few occasions including her address to the Democratic national Convention, Michelle Obama has talked about waking up every day in a house built by slaves. While various fact-checkers have rated this true, there are some facts they keep ignoring.Research showed that the workforce that build the Capitol building was part-slave therefore the same proportions must hold for the White House. This is a bit of a stretch since the White House was quite a bit smaller and built as a house rather than a capitol.