It’s my belief that most young border collies have the instinct to herd sheep somewhere deep in their mind
Most young border collies (and some other breeds) seem to have the instinct to herd sheep somewhere deep in their mind but some need a lot of encouragement to ‘bring it out’. I have no evidence for this, other than my own experience as a sheepdog trainer

I used to pride myself that I had never failed to get a young collie to work sheep – but not any more.
These days, my living depends on training sheepdogs, and I simply can’t afford to spend the time it sometimes takes to get a reluctant youngster to take an interest in working. Not only that, but we only have a limited number of kennels, so a dog which is extremely slow to develop an interest in sheep is actually occupying a space in which a more productive dog could be housed.
We also know that if a dog doesn’t want to work sheep, it’s usually easy to maintain its disinterest in them – and there is no shortage of people looking for a young border collie as a pet. If we’re able to offer them one which will be very easy to discourage from chasing sheep, that’s a bonus.
At the moment, Hettie’s not the slightest bit interested in sheep, but of course, this could change at any time. Our sheepdog training course last Saturday included two six year old dogs, neither of which had ever encountered sheep before. By the end of the day, both were working reasonably and showing remarkably good control over their sheep.
Sadly, if Hettie’s not keen to work sheep, I think it’s best to find her a home where she won’t feel pressurised. We have some prospective new owners coming to see her in a few days’ time, and if all goes well, I’m sure Hettie will make a wonderful pet for them.