even though she looks very young,she is twice older than my

even去掉
从句意来看 应该是“虽然” though就是虽然 尽管的意思
而even though 是指“即使”,即它所连接的情况未必出现
比如
He will come on time even though it rains. 即使下雨,他还是会准时来的.
这里“下雨”就是未必会出现的情况
而原句里她看起来很年轻 显然是实际存在的情况