From their April 2013 AER piece:
Analyzing these data, we find extremely small racial differences in mental functioning of children age 8 to 12 months. Absent controls, the mean white infant outscores the mean black infant by 0.055 standard deviation units — only a sliver of the one-standard-deviation racial gap typically observed at older ages. The raw scores for blacks are indistinguishable from Hispanics and Asians, who also slightly underperform whites. Adding interviewer fixed effects and controls for the child’s age, gender, socioeconomic status (SES) and prenatal circumstances further compresses the observed racial differences. With these covariates, we cannot reject equality in test scores across any of the racial/ethnic groups examined.
The piece is titled “Testing for Racial Differences in the Mental Ability of Young Children.” Versions of the piece are here, but I believe the final version is not yet in jstor.
Note that to the extent you treat parental IQ as affecting the IQ of the child through environment, these results are consistent with a wide variety of accounts of racial gaps in IQ. Still, there is no serious evidence, from these results, against the claim that the measured racial IQ gap is due to environment and environment alone.