Board Thread:General Discussion/@comment-5138166-20180117134112/@comment-28362353-20180118235235

Buu read one of Hercule's dirty magazines and wanted something like it so he split himself and made a female Majin called Miss Buu. Then they used the "Love-Love Beam" and started creating more Buus until there were so many that Majins could be considered a race. That's the official backstory of the majin race, straight from DB Online.