Yes Jack. I've heard of it before.  It happened with one of our midwives and
her sister. The sister was pregnant first and had similar problems to what
you've described. She started leaking at 16-18 weeks, needing a towel around
her chest towards the end of the pregnancy. She had really big hassles with
engorgement, mastitis x 3 and oversupply after the baby was born. For the
first 6 weeks she found attachment too painful and expressed and bottlefed
the baby.  Apparently there was no trauma or any visible reason for the
painful nipples. She was under the care of another LC, maybe it was thrush
(after 3 courses of Flucloxacillin) or maybe it was because the lactiferous
sinuses were so distended.  Anyway after 6 weeks she put the baby to the
breast and continued to breastfeed with no more problems until she got
pregnant again when the first was 11 months old.  Second baby had the same
problems during the pregnancy, an abundant supply postpartum but none of the
mastitis problems she had with the first.  She reported that she felt her
supply wasn't as huge second time around.  She weaned this baby about 2
months ago (at 14 mths) and still leaks overnight.
 The midwife sister reported the same problems when she got pregnant -
leaked from about 16 weeks, but didn't need the towel - just breast pads
were enough. She needed to wear breastpads to work too because she would
leak more when she was handling the babies.  After delivery she too had
massive oversupply, but was prepared for it. She weaned at 8 months saying
that her supply dropped off quickly when she returned to work, and now she
can hand express a drop or two only.
I suggested sage tea, but neither of them tried it.  They used cabbage
leaves and cold compresses when the older sister had mastitis.
Neither of them had any blood tests - they just accepted it as their genetic
lot!  As far as the midwife sister is aware nobody else in the family had
similar problems. Their mother got the usual management when they were born
ie no help, having problems, bottle feed! But she doesn't think she had
oversupply.
Hope you've found this interesting,
Denise
Brisbane, Australia