Welcome to Hulk's attempts to justify this decision and claim it's fully acceptable in a minute, but just to re-iterate, since splitting up with his wife of 12 years he's decided to start a relationship with her niece instead.
It's actually hard to figure out on what level it could be acceptable. Presumably, it's perfectly legal, but it doesn't make it any less weird.
According to a report Brazilian forward Hulk who currently plays for Shanghai SIPG in China, has started dating the niece of his former wife. The report does contain a quote from his representatives to say Hulk and his wife split up a few months ago so it's fine.
It seems that the player decided to go public in an effort to show "he had nothing to hide but it looks like everyone was about to find out so he's tried to maintain some control of the story.
There's no suggestion over how old the niece is, but Hulk has three children with his ex-wife so it takes on a whole new level of weird.
He was best known for his spells at Porto and Zenit, alongside having the name Hulk, but he will need to do something extra special in the last few years of his career to ensure that this isn't what we all remember him for.