An acronym is a word or name formed as an abbreviation from the initial components in a phrase or a word, usually individual letters (as in NATO or laser) and sometimes syllables (as in Benelux). There are no universal standards of the multiple names for such abbreviations and of their orthographic styling.
Son and daughter of your siblings and siblings-in-law. As with uncle and aunt, they're not your nieces and nephews by marriage, they're your nieces and nephews, plain and simple, even if they're your spouse's siblings' kids and don't have a single drop of blood in common with you.
The child your uncle has with someone to whom youâre not related is, therefore, 12.5 percent related to you. But in the case of double cousins, where both parents are siblings of your parents, the relationship is obviously doubled to 25 percentâthe same degree as with a half-sibling.