However, the Amgen spokesman condemned athletes who abused drugs in this way.

BBC: New drugs give cheats the edge

But the risk was about the same if their adoptive siblings -- those who had no biological connection to them -- had abused drugs.

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But 8.6% of those who had at least one biological parent who abused drugs had their own abuse problems versus 4.2% of adoptees whose biological parents did not have a history of drug abuse.

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He said that children were being let down by parents who abused alcohol and drugs.

BBC: Drugs revelation as town targets 'troubled' families

But these would not merely be performance-enhancing drugs to be abused by athletes.

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