A question for Mormons about polygamy?

It is a completely false doctrine/teaching and there are still some fringe groups who practice it today. This doctrine arose out of men who could not control their lust, I guess. It is so obvious to us that the bible teaches monogamy, but we can learn to not listen to any man, without checking out the bible ourselves. Also the bible says that in heaven there will not be marriage, but we will be like the angels of God. So where do they get that teaching of eternal marriage??