§ 52 SGB V

§ 52 SGB V reads(highlighting in the legal text by IntactiWiki):

Social code (SGB) Fifth Book (V) - Statutory health insurance - (Article 1 of the law from 20 December, 1988, FLG. I p. 2477)
§ 52 Limitation of benefits in the event of personal negligence

(1) If the insured has contracted an illness willfully or as a result of a crime or willful misdemeanor they have committed, the health insurance company can contribute to the costs of the benefits in an appropriate amount and refuse and reclaim the sickness benefit in whole or in part for the duration of this illness.

(2) If the insured person has contracted an illness through a medically not indicated aesthetic operation, a tattoo or a piercing, the health insurance company has to pay the insured person a reasonable amount of the costs and the sickness benefit in whole or in part for the duration of this treatment to fail or reclaim.

Non-binding comment from IntactiWiki:

This paragraph is suitable to financially prosecute people who voluntarily submit to HGM for aesthetic reasons. However, it will probably not apply to minors, since the German Circumcision Act currently widely protects their parents in their decision. With FGM, § 226a StGB is available as a legal tool.