They were indeed a remarkable dynasty and, for quick reference, both have worthy biographies on Wikipedia. Freeman Dyson was born at Crowthorne Berkshire while his father George Dyson (later Sir George) was music master at Wellington College. Both moved to Winchester College as music master and scholar respectively and both contributed expertise in the two world wars albeit about the contrasting topics of hand grenades and bomber aircraft formation! It can be said that both were prodigies. George Dyson was the son of a blacksmith and a weaver from Halifax (on an American music publisher's website, I found this referred to as Halifax, Nova Scotia, but they graciously corrected this when it was pointed out that this was Halifax, Yorkshire, England!). George Dyson was FRCO at 16 and had a most distinguished musical career, culminating in Director of the RCM. His works include large-scale orchestral and choral ones as well as the possibly better-known songs and Evening canticles. I can't offer any direct knowledge of Freeman Dyson, but the Wikipedia article gives hints of extraordinary gifts from a very early age, and, in answer to Colin's point, I guess that at Winchester and later Cambridge he was exposed to exceptional artistic and intellectual environments. Later, moving to America, he reached the pinnacle of a scientific career there. In their different fields, both were men of outstanding distinction.
I should perhaps have mentioned this earlier, but Freeman Dyson, son of Sir George Dyson, died on 28 February. The earliest recollection I can recall of Sir George is that some of the piano pieces I laboured through as a small boy were from his pen. But since I later followed a career in science rather than music it is his son, Freeman, whose work I am more familiar with. It isn't for me to take readers through the achievements of either of them, but they were both more than notable in their respective fields. I wonder whether the unusually broad and sometimes controversial aspects of Freeman's scientific career might have been encouraged by his exposure to the Arts as a youngster - he was certainly one who took an interest in, and contributed to, a bigger picture than that which most physicists seem content to look at.
What a gifted pair they were, covering such a wide intellectual spectrum between them.
Those of you that enjoyed Jennifer Bate's Bach from the RAH may be interested to know that, on YouTube, there are 3 LPs worth of Ralph Davier / Ake Leven, including over 50 mins of Bach. Also an LP of "French". and "Encores." All very welcome.