Prof Denny Mitchison - and the Haldane gene at work

Writing my biography of J.S.Haldane, I waited a fair while before contacting the living relatives. A sounder game is to rush in there early, while their health holds good, but it seems there's no need of that with the Haldane clan. Denny Mitchison has just been featured in The Guardian as the world's oldest working professor, at 90
When I arrived for our interview, he and his wife were just leaving the house for a regular route along the edge of Richmond Park. I marched off with them. Beside the memories (Denny grew up in his grandfather's house and practised his early science in the Haldane home laboratory at Cherwell in Oxford, now the site of Wolfson College), what was special for me was catching that twinkle in his eye, seeing signs of the grandfather stil vital in the man.
His wife speculated that Professor Denny's groundbreaking research into TB stemmed from his experience of his brother's death - which fitted in neatly with my speculation about J.S.Haldane, who moved to a career in medicine and lung specialism after witnessing his own beloved brother's death from diphtheria.
Denny was having nothing to do with the coincidence. Fair enugh. I still follow Haldane's dictum, that nothing can be truly seen outside of its environment.