A recent book that backs this up is:

Born of Lakes and Plains, by Anne F. Hyde (Norton). “A new way of looking at the American West emerges in this history of the mixing and marrying of Indigenous people and settlers. Beginning with the fur trade, Hyde shows how marriage and procreation were crucial to integrating newcomers and building alliances. Commerce relied on networks of kin, and, as Native American clans would share knowledge only with those they considered family, mixed-descent children were vital intermediaries. The stories of five families through the nineteenth century illustrate how these intermediaries were also vulnerable to racist and expansionist policies. Though some were forced to hide their heritage, Hyde highlights their acts of agency, and tells "a narrative of our past with shared blood at its heart."