I want to know the answer to the following question:
Which Latin father described the belief that Jesus' siblings were his cousins?
All the background I'm provided with is that "While the Orthodox Churches hold the position articulated in the Protoevangelium of James that Jesus' brothers and sisters are older children of Joseph the Betrothed, step-siblings from an earlier marriage that left him widowed, Roman Catholic teaching follows the Latin father Jerome in considering them Jesus' cousins.". Is that enough to answer the question?
Answer: yes