biosibling

plural biosiblings

1. A biological sibling.

   Indeed, biosiblings are more correlated for weight than they are for obesity.

   2012, Michael Beenstock, “Correlation within the Family”, in Heredity, Family, and Inequality: A Critique of Social Sciences, Cambridge, Mass.; London: The MIT Press, →ISBN, page 72

   3 more examples

   The child may also experience divided loyalties between his natural siblings and stepsiblings, particularly where a stepsibling is close in age and becomes a buddy to the child, thereby usurping the exclusive role his biosibling may formerly have had.

   1981, Helen Crohn, Holly Brown, Libby Walker, Joan Beir, “Understanding and Treating the Child in the Remarried Family”, in Irving R. Stuart, Lawrence Edwin Abt, editors, Children of Separation and Divorce: Management and Treatment, Van Nostrand Reinhold Company, →ISBN, part IV (Treatment Within the Family Unit), page 302

   A typical minor or grown stepchild may[…]have biosiblings, stepsiblings, and/or half-siblings in the same home, in their other bioparent’s home, in both homes, or neither.

   2001, Peter K. Gerlach, “Stepfamily Realities”, in Build a High-nurturance Stepfamily: A Guidebook for Co-parents (Stepfamily inFormation Series; Divorce-Prevention Series; volume 4), Xlibris, →ISBN, part 1 (Foundations), page 86

   The winning bidders were so thrilled with the outcome that they hired Shoko to bump with Raimundo again (they were broken up at this point, which made it waaaay awkward but business is business and pleasure is pleasure), so the second pregg she’s carrying now is biosiblings with the first.

   2011, Megan McCafferty, Bumped, Balzer + Bray, an imprint of HarperCollinsPublishers, →ISBN, page 49

   Synonyms: biosib, blood sibling