Geni is not supposed to be a work of lurid fiction.
Somebody must have made a bad merge. Or two or three.
This person is stated to be:
Alexander Stewart, Lord Avondale, Alexander Stewart, John Stewart, Earl of Atholl, Walter Stuart, Alexander, Margaret Methvin, Alexander, Eleanor Sinclair and Elizabeth Arnot
(I can't even find him in my FTM file, which is probably where my version came from!)