Are they the same? As both are related to sexual activity between close relatives.
closed as off-topic by Remi.b, David, kmm, theforestecologist♦, Bryan Krause♦ Dec 7 '18 at 4:46
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Incest is a human concept defined by law and social conventions. For example, see a definition of the word: "sexual intercourse between persons so closely related that they are forbidden by law to marry".
A person who was adopted may have siblings who are genetically more different from them than other people they could legally have romantic relationships with. In many countries you may marry your cousin, but not your foster brother/sister born on the other side of the world.
Anthropologist Claude Lévi-Strauss pioneered the study of the universality of the notion of incest; romantic relationships with family members is culturally forbidden in pretty much all cultures around the globe. But why? One of the explanations is linked to the notion of inbreeding.
Inbreeding (mating between genetically closely related individuals) favors homozygosity, and as a consequence a certain genetic homogeneity in which there is often not a "functional" allele to compensate for the "broken" one - the consequences on physiology and mental cognitive abilities are often dramatic (see Roberts, BMJ, 1967 or this article from Stanford @ the Tech, for example); it is hypothesized that this is the reason why evolution selected behaviors that avoid the risks linked to inbreeding.
Incest and inbreeding are different concepts. Incest involves crossbreeding between close relatives. Inbreeding is a broader concept. It can be a connection between relatives or self-pollination. UPD: This is certainly not a journal article, but..... https://en.wikipedia.org/wiki/Inbreeding