Wombat
I get what you are saying but I don't think you are correct in implying (?) that those with middling GCSEs should give up any thoughts of doing medicine.
Have you read Sheffields medical school admissions policy? If you had you will see that the OPs DN would not be disadvantaged in any way by her GCSE grades.
Here is relevent paragraph:
In Stage 1, applicants compete against the minimum requirements. There is no compensation between academic attainment and UKCAT attainment - both requirements must be met. While many applicants exceed the minimum academic and UKCAT requirements, we do not rank applicants according to academic or UKCAT attainment, and there is no advantage in our selection process to those who exceed the minimum requirements
As with all medical schools the requirements are clearly spelt out. These are Sheffields GCSE requirements.
GCSE passes at grade C or above in Mathematics, English and the Sciences
(which may be dual awards).
You should have at least six A grades in GCSE subjects.
The six A grades may include Mathematics, English and the sciences.
Acceptable science GCSEs include: Biology, Chemistry, Environmental Science, Mathematics, Physics, Psychology, Sciences (dual awards)
Please note:
The GCSE requirements should have been met by the point of application.
The relevant GCSEs should be studied for no longer than two years.
The six A grades must all be obtained in the same sitting.
The required C grades in Mathematics, English and the Sciences do not need to
be obtained in the same year as the six A grades.
We do not accept GCSE resits.
So although things are not looking great for the OPs DN if she pulls her fingers out and fulfills all the other entry requirement (impressive UKCAT, A2s, work experience, PS, etc) she will not be disadvantaged if she applies to Sheffield or another medical school that operates a similar pass/fail selection criteria for GCSE's.
Medical schools put an awful lot of thought into their admissions requirements. If medical schools such as Sheffield who only require 6As at GCSE wanted their candidates to have higher GCSE grades they would have an admissions policy that required or favoured them.