It also massively screws up his family tree and turns it into a complete clusterfuck, since Sparks is being raised by Shadow (his great grandfather) after his mom suffered a Kaiju-induced existence removal which caused his biological dad (Mighty's grandson) to have a breakdown and bail until well into his teens, so he views Shadow as being his father. So it not only means that Sonic is directly related to fucking MIGHTY, but he is simultaneously being raised by Shadow (his husband) who he views as his effective father, but Zee (his wife) is his great grandmother PLUS his son and half-daughter (Shadow and Zee) are in fact his own grandparents, along with Mighty being his OTHER grandpa from his father's side and Tails being BOTH his great uncle and his brother at once. His son's wife is also Amy and Rouge's kid thanks to assistance from Knuckles, so it gets even more nightmarishly convoluted when you stop and think about it, and that's without factoring in Shadow's branch too. And whoever Sparks gets with in the future will only make it worse.
Sonic has utterly FUCKED his family tree beyond any hope of repair.