There is a great swell of people pushing the idea of mixed-race people are “more fit” or “stronger” or “healthier”. The language they use for this new mixed race population is strangely belligerent, calling them “stronger” and “superior”. It seems to be a kind of mixed-race supremacism – distinct from the “folk” focus of racial nationalist groups – but with very little effort to find real data for their claims.
In general, for characteristics that are affected by a large number of genes (which is likely usually the case), a mixed-race group would be expected to have characteristics that on average are intermediate between those of the averages of the parental/ancestral races.
If the parents/ancestors were atypical compared to their racial average(s), then this would to some degree affect this expectation. However, one factor affecting the relatives of atypical parents may be regression to the mean effects.
There is a widespread belief that race mixing is beneficial by decreasing inbreeding. However, the population size needed to avoid problems caused by inbreeding is small and is even smaller if there is even a small genetic exchange with neighboring groups from the same race. See the article on inbreeding depression.
Instead, there may be increased risks of negative effects for both children and parents, caused by factors such as
Genetic outbreeding depression. Increased risk of relationship problems (including violence and homicide) in interracial relationships. Identity problems for mixed-race children by not belonging to any racial group. Social isolation for mixed-race children by not belonging to any racial group. Disapproval by society or specific groups against interracial relationships. For example, many Jewish individuals, organizations and the state of Israel actively oppose, campaign against, and prohibit Jews from marrying non-Jews. Genetic similarity theory predicts that the parents and other relatives of mixed-race children will feel less close to the mixed-race children. It also predicts that other persons belonging to the races of the parents will feel less close the mixed-race children. In turn, mixed-race children are predicted to will feel less close to their parents, other relatives, and to other persons belonging to the races of the parents. This may cause various problems for the children, the parents, and others. Extensive race mixing is one proposed explanation for the fall of many civilizations due to dysgenic effects.
Even if there were no dysgenic effects from race mixing, for society large scale race mixing may still cause problems, due to factors such as the appearance of new mixed race groups that may feel more or less alienated from their ancestral races. This may increase the ethnic heterogeneity in a society and associated negative societal effects.
Race mixing may be especially problematic for societies where the predominant race is a high K race (see the article about the Differential K theory) with a high degree of altruism and a consequent extensive welfare system. This means that immigrant race mixers from a low K race may have many children without having to support the children themselves and who are instead supported by the welfare systems. (Immigrants from low K races may also have many children within their own group and who are supported by welfare systems paid for by the high K race.)
From the viewpoint of transmitting a parent's genetics to the next generation, mixed race children will transmit less. This since a co-parent from another race will have more dissimilar genetics than a co-parent from the same race. For example, the measured genetic differences between human races is argued to imply that a White English parent will in relative terms be almost twice as closely related to a child with a White English co-parent as to a mixed race child with a Black Bantu co-parent. In terms of the genetic interests of a parent, this is argued to imply that having a non mixed child is almost the equivalent to having twice the number of such mixed race children. Another stated example is that a parent will be genetically closer to an average (and in some cases to every) individual of the parent's own race than to the parent's own mixed race child with a co-parent from a genetically distant race