I gleaned the following information from the SS David & Cyfelanch Parish records booklets. Hopkin Morris was baptized on 8/27/1826. His parents were Isaac Morris and Anne Jones. Isaac was a farmer. [Thus the Isaac Morris in the 1851 census was named after his grandfather.] Isaac and Jane were married 2/8/1823. The family was living at Erthrimgenol. Only other child in the records was Rachel Morris baptized 5/30/1824. At that time family was living at Cythylyd. No other information on Isaac Morris.
However, there is plenty of info on Anne Jones and her family. Anne was baptized on 4/25/1802. Ann's parents were Richard Jones and [probably] Catherine Hopkin. [I think the name Hopkin cements the connection with Catherine.] They were married 8/24/1794. Other children were Catherine, baptized 12/26/1798, Edward, baptized 12/19/1815, and John. [They are two John Jones born around 1800 whose father was a Richard Jones. However, at that time the mother's name was not recorded.] No further concert info on Richard Jones other than he was a farmer.
Catherine Hopkin was baptized on 8/16/1772. Her father was John Hopkin. Other children of John were Elinor, baptized 5/14/1777, Elizabeth, 3/26/1774, and John, 4/22/1770. No further concert info Catherine's father. I suspect that one could trace her sibling's and their kids from the parish records.
If you are interested, you can obtain the parish records from the Glamorgan Family History Society. They have a website, just do a search.