Table 3.

Rates of Drug Abuse in Adopted Children of Biological Parents, Adoptive Offspring of Adoptive Parents, and Biological and Adoptive Siblings of Adopted Children With and Without Drug Abuse

		% (95% CI)
Proband	Relative	Rate of Drug Abuse in Relative When Proband Has Drug Abuse	Rate of Drug Abuse in Relative When Proband Does Not Have Drug Abuse
Biological parent (any)	Adopted away biological offspring	8.6 (7.0–10.4)	4.2 (4.0–4.6)
Biological father	Adopted away biological offspring	9.9 (7.2–12.1)	4.4 (4.1–4.7)
Biological mother	Adopted away biological offspring	8.2 (6.3–10.5)	4.4 (4.1–4.7)
Adoptive parent (any)	Adoptive offspring	6.8 (3.6–11.6)	4.5 (4.2–4.8)
Adopted child	Biological full sibling	10.7 (7.6–14.5)	6.1 (5.6–6.7)
Adopted child	Biological half sibling	7.4 (6.3–8.5)	5.3 (5.1–5.5)
Adopted child	Adoptive sibling	6.2 (4.5–8.1)	3.2 (3.0–3.5)