Did Jesus have siblings (brothers/sisters)?

I am doing a bible study with my dad, who is a protestant. His beliefs are that Jesus had brothers and sisters. I am confident in my answer that he did not have any true brothers or sisters, as Mary was a perpetual virgin. I am confident in this, BUT need the info to back it up. How does a Catholic respond to someone who is certain he had brothers (example James or others).
Thank you

The following links should help you understand the Church’s position on whether Jesus had brothers. If you have any further questions, please contact Catholic Answers directly.

Recommended Reading:

*] Doesn’t Scripture imply that Mary had children other than Jesus?
*] Did Jesus have brothers?
*] Perpetual Virginity: Why is this important?
*] Mary: Ever Virgin

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit www.catholic.com.