Answered April 18th, 2019

Jeff Bagwell hits his 38th homer of the year to set a new Astros single-season record. He'd ultimately pass this mark five times in his career, with his 47 in 2000 serving as the current team record.

Who was the first Astros player with 38 HR in a season?
Interpreted as:
Who was the first Astros player with 38 or more HR in a season?