Hi Chanelferris. In reply to your question about Andrew's 1978 s JM Barrie and the Lost Boys: it's not a documentary, but a mini-series running to 4h 30 and is under copyright, so wouldn't be available to watch on YouTube or any other site for free. You can buy copies, new and used, on Amazon: https://www.amazon.co.uk/J-M-Barrie-Lost-Boys-DVD/dp/B0002PC2EA/ref=sr_1_7?s=dvd&ie=UTF8&qid=1476378757&sr=1-7&keywords=the+lost+boys
It's a great docudrama, and the best portrayal of Barrie ever (Finding Neverland doesn't come anywhere near!), so well worth buying and keeping. Enjoy.
Daphne du Maurier had some strange ideas about some things, so it's not really a surprise that she got in her head the emphysema was inherited from their ancestors. People of that generation used to be heavy smokers, and the smog in London prevailing at the time wouldn't have helped.