My opinion is correct on a common sense level and requires no source.
As has been mentioned, there is no logic in distinguishing between full and half siblings. The poskim discuss how to behave with step-siblings who are not biologically related. The tendency is to treat them as if they were biological siblings in regards to yichud and normal family life . Hence it is obvious that half and full siblings can be misyached etc…
Certainly, though, biologically related siblings are arayos and may not have relations or ever marry.
For a full treatment of the issue, see Tzitz Eliezer Chelek 6, Siman 40, perek 20 and 21. A very comprehensive and lengthy source. Read it, please.
In summary, behave with your half sibling as you would with your full sibling.