Bryan Johnson’s manual for modern intimacy. (Source: Instagram/@bryanjohnson) Many parents feel uncomfortable discussing sexuality with their children, something experts point out begins with compassionate discussions about gender. To initiate a discussion with his young adult son on intimacy, American biohacker Bryan Johnson wrote an instruction manual after his kid raised questions on the subject. “We have this entire generation of people who have not been educated on how to make love, and what exactly happens,” the longevity entrepreneur told Business Insider . “When you put your hand on your partner and move it fast, the body processes that touch differently. If you move it slower than 3 cm per second, the nerve fibres say, ‘I feel intimate .’ The speed of touch communicates to the nerve fibres how we are connected…People read this (manual) and went, ‘This is like 50 Shades of Grey, longevity version,'” he added.…