Can you let us know where you learned this? The UN Convention on the Prevention and Punishment of the Crime of Genocide, which is the foundational piece of this in international law, restricts the definition of genocide as follows:

genocide means any of the following acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such :

(a) Killing members of the group;

(b) Causing serious bodily or mental harm to members of the group;

(c) Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part;

(d) Imposing measures intended to prevent births within the group;

(e) Forcibly transferring children of the group to another group.

The original drafts of the document also included mass killings for political purposes, but that portion of the definition was removed under pressure from the Soviet Union. Is that possibly what you're referring to?

The UN convention definition is likewise enshrined in US law and in UK law.