There are brochures by reputable sources, for example the british NHS, showing being trans has biological connections.
There are differences in brains of women and men so a mismatch is possible.
Its literally a womans brain in a mans body and vice versa. So its really how people feel.
Its explained with pictures and can be translated into another language.
http://www.gires.org.uk/assets/DOH-Assets/pdf/doh-transgender-experiences.pdfwww.translate.google.com
If its biological its nobodys fault... not an upbringing or whatever ... and its not likely to be a phase...
Some people make a comparison with a twin... they will be like their male/female twin, with the same sense of humour...
one strategy could be to explain your feelings and show some materials ...
here is another resource, written from a cis persons point of view:
http://www.acceptingdad.com/2013/08/05/to-the-unicorns-dad/There are a few points included which might help understand.
Well baseline is ... what do you expect from it ?
Could they raise doubts which might drag you down ?
Or do you feel they might be understanding and you might have a better time ?
*hugs*