Uncertainty & Optimism

My sister has asked to borrow quite a bit of money from me to open up a restaurant with her husband. I am inclined to loan her the money because I think she is talented and experienced and also because she is my little sister. When she and her husband came to ask for the money they also told me that her husband was on methadone and that he had been for 10 months. They said it was not a big deal but that they didn’t want me to find out from someone else after the fact and think that they had been hiding it to get the loan. I guess he got addicted to painkillers after back surgery a few years ago. I never knew that it was a problem but I guess it got pretty bad for a while. Anyway, I don’t know much about methadone. If he has been OK for 10 months does that mean he is going to be OK for ever, probably? I know that you cannot give guarantees but do you think it is likely going to be a problem for them in this upcoming business venture, considering that he has been clean for almost a year now already.