More than 400 youngsters are being diagnosed and treated for chlamydia, gonorrhoea and syphilis each year.
Information from Health Protection Scotland showed around a quarter of those found with infections were in the NHS Lothian area.
And while most were aged 15, around a quarter were 14 with some reported as young as 12. NHS Lothian and NHS Lanarkshire reported cases of 12-year-olds being diagnosed with chlamydia, while gonorrhea and syphilis was found in youngsters of the same age by NHS Greater Glasgow and Clyde.
The Scottish Government says it is down to local authorities to provide sex education.
But the Tories have condemned the comment, with health spokesman Jackson Carlaw saying: "This is a public health issue and it should be the Public Health Minister's priority to provide leadership. Parents would expect nothing less."