In more depressing news: 60% of cancers may not be due to lifestyle. The correct phrase would probably be "known lifestyle choices". But seriously, shouldn't people be surprised lifestyle only accounts for 40%. What if I rewrote the entry paragraph in the following way:

Nearly half of low intelligence diagnosed in the UK each year - over 130,000 in total - are caused by avoidable life choices including not reading, debating, or thinking about interesting problems.