I have to hard disagree here and i'd also like to mention (without accusing you of anything, ofc) that transphobes routinely use "the killer isn't actually trans, it says so right in the film" as an excuse to shield these films from accusations of transphobia and to engage with the harmful, actively damaging concepts they've inject into the public subconscious over the decades. I see Psycho as clearly transphobic even if we view Bates as a cismale crossdresser. I don't share that view, we almost exclusively see the character from the perspective of an outside observer, narrated in a way that is oblivious to authentic trans experiences and it's impossible to judge against that background if the story is about a man wearing drag or about an egg confining her true self to crossdressing episodes that she can seperate from her everyday male gender performance to maintain a self image compatible with Amerikan mid-century society. But that is irrelevant to the films transphobia. What makes Psycho so dangerously transphobic is how it deals with the validity of trans identities: Having a psychiatrist barge in at the end and declare that the murderer was "not a REAL transsexual" without ever having talked to Bates is purest transmedicalism and standard for films centered around killers violating gender norms. You see the exact same "not a REAL transsexual" expert statement in Silence of the Lambs and in Dressed to Kill (i think the Cormoran novels by J.K. Rowling do the same with their killers, but i'll never read anything of that madwoman's drivel again). And it is the very core of these works' transphobia to deny the identity of the killers. I don't care if a film portrays a trans woman as a serial killer if she's an authentic portrayal of a heckin valid trans girl doing trans things, except she just happens to have a basement full of terf meat she serves as a caterer at Republican party conventions. Honestly, i'd watch the shit out of that if it was narrated from a trans perspective. Being accepted means we do not need to be exempted from being the villains in movies, everybody loves a good villain. No, what makes me view these films as the prime example of trans-exterminatory propaganda is that we get gender-nonconforming killers and they are always framed as being "not actually trans" because to the transphobe, trans people aren't real. The killers are therefore misgendered and deadnamed throughout the film to the point that we do not even get to learn their chosen names, or get to know anything about their gender identity from their own perspective. We only see through the eyes of Buffalo Deadname when she has her nightvision goggles on and tries to murder Agent Starling or when she threatens to use the hose again. We only see through the eyes of Bates when Bates is using the peepholes and stabbing the victim. Their own perspectives are used exclusively for vojeuristic violence against cis women. Anything else about their entire existence is reduced to the outside perspective, which is a cissie imagination of what it's like when somebody "is faking transness". How can anything be more transphobic than that?

¿Por qué no los dos? Would the audience have been as unsettled, or seen the killer as quite so transgressive, if the Mother character had instead been a Father? Even if the film isn't explicitly anti–trans, it still relies on transphobia brought to the film by the audience for at least some of its shock value.