Is a registered sex offender that looked up under age porn on the internet aloud to be around children and live in the same house please help asap

It would depend on the terms of the judgment of conviction. What state or country was it, and what was the specific offense for which this person was convicted?

Sex offenders are generally rated at levels. The lower the level the less likely they are to repeat.

Without knowing the level, the specific crime, the terms of probation and the area where he was convicted its impossible to answer.

But if the crime was possession of kiddie porn, its unlikely he would be allowed around children.