Your data look similar to this (as you've described them):
load patients
data=[{'name'} {'gender'} {'age'}; LastName Gender num2cell(Age)]
You just use strcmp to compare strings, and specify you want the rows where gender contains 'm' and column 1
data(strcmp(data(:,2),'Male'),1) % obviously you'll use 'm' in your case
If it were me, I'd put these in a table and use strings, it's so much better!
t=array2table(data(2:end,:),'VariableNames',data(1,:));
t.name=string(t.name);
t.gender=categorical(t.gender);
t.age=cell2mat(t.age);
t.name(t.gender=="Male")
