Is it against the law for ex convicts to be around kids?

No, it is not against the law for ex convicts to be around kids. Ex convicts may be subject to parole or probation conditions which may require them to agree to stay away from kids or places where kids congregate, and this would be common in the case of a sex offender who is on parole. Ex convicts may be prohibited from obtaining certain jobs where a professional license is required.