For modern scientific rebuttals to race science, I'd start with Sasha Gusev and Eric Turkheimer. You'll read about things like missing heritability and the methodological problems of twin studies (which are grave). I'd also read Cosma Shalizi's "g, a statistical myth", which is also fun just from a sort of mid-level math/stat perspective. A classic in the field that still holds up is Ned Block's "Race, Genes, and IQ", written as a response to The Bell Curve.
I don't have offhand good links to critiques of Gould that are on any site I would recommend you read.