Sorry for long delay in reply. The basic picture is that the mother-in-law had a cancerous lump in her leg. On a day in the middle of August 2013 we had intercourse, then my wife went off for a few days at the beach with her parents, then they all came back together and about a week or so later her mother went into hospital, into "nuclear medicine" had an isotope to show them the ganglia, etc. The rest as i have described it above. My wife eats a lot of fried meat, hardly any vegetables, a lot of pulses (lentils, beans, etc.), no fish except for lots of tuna (which for me is a no-no), drinks lots of Coca-Cola, although due to my insistence things have become more normal over the years. The meat she eats is normal quality, not necessarily cheap ever. And she doesn't eat any processed food, everything is fresh.
In 33% of cases, the disease our son has is a spontaneous mutation ("de novo"), in the other 66% it is inherited through the mother. The mutation is always on the X chromosome. Only boys really get it because if they have a mutation on their X chromosome they do not have another X to fall back on.