Visitation rules for inmates convicted of sexual offenses, particularly those involving minors, are among the most carefully regulated in the correctional system and vary significantly by facility, state, and the specific nature of the conviction.
In general, adult family members who are not minors and who pass the standard background check can often still visit, including siblings, depending on the facility's policies and any specific conditions attached to the sentence or supervision order. However, contact with minors is almost universally restricted for inmates convicted of sexual offenses against children. If any of the siblings are under 18, visitation with them is likely prohibited without explicit court approval regardless of the family relationship.
The specific restrictions attached to your loved one's case are what matter most here. Some convictions come with conditions written directly into the sentencing order that restrict contact with certain categories of people beyond what the facility's standard policies require. Those conditions override facility policy and cannot be waived by the warden alone.
The right first call is to the facility to ask specifically what visitation restrictions apply to this inmate given the nature of the conviction. Be direct and factual when you call. The facility can tell you which categories of visitors are permitted, whether minor siblings are allowed, and what documentation or approval process might exist for any exceptions.
If the answer from the facility is unclear or if you believe restrictions are being applied incorrectly, consulting with an attorney who handles correctional law is the appropriate next step. Getting accurate information specific to your situation is essential before making any visit attempt.