Final answer:
J.P. Morgan learned about the banking industry from his father, Junius Spencer Morgan, a successful London banker.
Step-by-step explanation:
The industry that J.P. Morgan learned about from his father was banking. Junius Spencer Morgan, J.P. Morgan's father, was a prominent London banker and became successful in the field while working in the import business during the 1830s. He then created a partnership with another banker and eventually formed J. S. Morgan & Co. Taking after his father, J.P. Morgan continued the legacy in the United States as a skilled financier, eventually forming his own company, J. Pierpont Morgan and Company. While J.P. Morgan's investments spanned various industries, his initial and foundational knowledge came from the banking sector, which was critical to his future investments in emerging industries such as steel and railroads.