There is provided a multistage polymer that comprises (a) at least one soft polymer having glass transition temperature of 40° C. or lower, and (b) at least one hard polymer having glass transition temperature higher than 40° C., wherein the glass transition temperature of said hard polymer is at least 10° C. higher than the glass transition temperature of said soft polymer, wherein the weight ratio of said hard polymer to said soft polymer is from 1.01:1 to 100:1, and wherein said multistage polymer, after exposure to liquid water followed by drying at temperatures below 100° C., shows maximum thermal transition temperature in an atmosphere of 0% relative humidity that differs by 20° C. or less from the maximum thermal transition temperature in an atmosphere of 75% relative humidity. Also provided are an aqueous latex comprising such a multistage polymer, a composition comprising a powder comprising such a multistage polymer, a solution comprising such a multistage polymer, and a method of styling hair comprising applying such a multistage polymer to the hair.