18 Pa. Stat. § 5110
Whoever, being of the age of eighteen years and upwards, after having been convicted of the crime or attempt to commit the crime of treason, murder, voluntary manslaughter, sodomy, burglary, entering with intent to steal, larceny, rape, robbery, arson, mayhem, kidnapping, sale of narcotics, perjury, abortion, pandering, incest, or any offense committed or attempted to be committed through the instrumentality of or with the aid of a deadly weapon or gunpowder or other explosive substances or corrosive fluid, wherein a minor child under the age of eighteen (18) years is involved as a principal or as an accomplice or as accessory before or after the fact or as an associate, may, upon conviction of any of the aforementioned crimes, be sentenced to imprisonment for a term, the maximum of which shall not be more than twice the longest term otherwise prescribe by law upon a conviction of the crime in question.
In all proceedings under the provisions of this section, knowledge of the minor's age shall be presumed in the absence of proof of the contrary.
18 P.S. § 5110