From Wiki...
The frequency of lactose intolerance ranges from 5% in Northern European to more than 90% in some African and Asian countries.[7] Some have argued that this links intolerance to natural selection favoring lactase-persistent individuals, but it is also consistent with a physiological response to decrease lactase production when it is not needed in cultures in which dairy products are not an available food source.[8]
It’s not like cows and goats are endangered species.
Lactose tolerance is environmental, not racial. Populations which have depended on milk tend to have higher tolerance to lactose. For example, Japanese are relatively intolerant, but Mongolians are tolerant. Same for the Masaii vs most other sub-Saharan Africans and northern Europeans vs Southern Europeans. Herding behavior is a better marker than race.
She also mistakes why milk was promoted for blacks, besides the push by the dairy lobby. Blacks in northern climates are notorious for developing rickets, a disease caused by insufficient Vit D and calcium. Vit D milk was promoted as a simple and healthy way to fight that. While lactose intolerance in blacks might not have been taken into consideration, there’s a big difference between ignorance and racism.