As a personal story, when I first studied guitar, I could not sing in tune, play by ear and had rhythm problems. My guitar teacher did not know that pitch and rhythm could be vastly improved. That was the common belief.
However, when I got to music college, Berklee College of Music, I took Ear Training.
Then, while at Columbia University, I researched scholarly studies investigating improving pitch and rhythm and the concept of "Talent".
I found that the origin of the word "Talent" was a Roman coin, and with enough "Talents" one could do anything. In fact, every case of perfect pitch was associated with early learning. In fact, everyone can acquire the skills people associate with talent with proper instruction.
Using my research and experience, I learned to incorporate ear training into all my music lessons.
While ear training has incredible lifetime benefits at an early age, it is never too late. I had my ear training at age 17, and it was the most important music class I ever took.