1. A composition comprising, in a physiologically acceptable medium: a siloxane resin, a silsesquioxane resin, and at least one non-volatile oil, wherein:
the siloxane resin comprises at least 80 mol % of:
at least one M unit, (R′3SiO1/2)a; and
at least one Q unit, (SiO4/2)b;
R′ independently represents an alkyl group comprising 1 to 8 carbon atoms, an aryl group, a carbinol group or an amino group;
at least 95 mol % of the R′ groups are alkyl groups;
a and b are greater than 0;
a ratio of a/b is between 0.5 and 1.5;
the silsesquioxane resin comprises at least 80 mol % of at least one T unit, (R″SiO3/2);
R″ independently represents an alkyl group comprising 1 to 8 carbon atoms, an aryl group, a carbinol group or an amino group;
at least 80 mol % of the R″ groups are propyl groups;
a weight ratio of the siloxane resin to the silsesquioxane resin is between 1/99 and 99/1;
the siloxane resin and the silsesquioxane resin are not bonded to one another by covalent bonds; and
the number of the at least one M unit is less than the number of the at least one T unit plus the at least one Q unit.